Evaluation of root and canal morphology of maxillary molars in a Southern Chinese subpopulation: a cone-beam computed tomographic study

Previous studies using cone-beam computed tomography (CBCT) in different ethnic populations showed generality, similarity and diversity in root and canal morphology. Data about the southern Chinese population is scanty. This study was aimed at investigating the variations in root canal configuration in maxillary first (1 MM) and second molars (2 MM) of a southern Chinese subpopulation using CBCT. A total of 337 male and 310 female adults from a southern Chinese population with healthy, untreated, well-developed maxillary molars were enrolled. All 953 1 MM and 1,066 2 MM were analysed in vivo using CBCT scanning. The number of roots and canals, the canal configuration (Vertucci's classification) and the presence of additional mesiobuccal canals (MB2) were recorded. In 1 MM, over 97% had 3 separate roots, 31% had 3 canals and 68.1% had 4. In 2 MM, over 70% had 3 roots and 20% had 2 roots, and 67.1% had 3 canals and 24% had 4 canals. The prevalence of MB2 canals in 1 MM and 2 MM is 68.3% and 23.8%, respectively. When MB2 was present, the most common type of MB root canal configuration of 1 MM and 2 MM was type IV and III. A 22-variant category of root canal system of maxillary molars was devised. In conclusions, Southern Chinese subpopulation had a high MB2 prevalence of 68.3% in 1 MM, with the most common variants being the newly-modified category variant XIV and XV. Some uncommon variants were also found in this study.